[PATCH] D18046: [X86] Providing correct unwind info in function epilogue

[Matthias Braun via Phabricator via llvm-commits]

MatzeB added a comment.

Sorry for being so late to the review.

I'm very concerned about adding members to MachineBasicBlock, that makes this information effectively part of our machine representation that needs to be modified appropriately by transformation passes. In that respect it is not natural and I expect maintenance problems long term.

I know this was already discussed but I fail to find the exact reasons why producing all the CFA information as part of the AsmPrinter was dismissed.
Intuitively I would expect it to be very well possible to do some abstract simulation of the stack pointer during emission (possibly with target callbacks helping out to determine which instructions modify the stack/callframe access in which way). And I would take such a solution any day over introducing more "state" into machine functions/blocks. Even if it is more/complexer code than doing it as part of Prolog Epilog emission.


Repository:
  rL LLVM

https://reviews.llvm.org/D18046